Multi-year incubation experiments boost confidence in model projections of long-term soil carbon dynamics

• DOI: 10.1002/essoar.10508550.1
• Publication Date: 2021-10-29T20:24:36Z
• Authors: Jianwei Li; Siyang Jian; Gangsheng Wang; Laurel Kluber; Christopher Schadt; Junyi Liang; Melanie Mayes
• Keywords: Carbon Sequestration; Atmospheric Science; Ecosystem Resilience; Science; Soil Science; Carbon Dynamics in Peatland Ecosystems; Forests; Models, Biological; 01 natural sciences; Article; Agricultural and Biological Sciences; Soil; Arctic Permafrost Dynamics and Climate Change; Carbon Feedback; Soil Carbon Sequestration; Soil Microbiology; Ohio; 0105 earth and related environmental sciences; 2. Zero hunger; Soil Fertility; Ecology; Q; Life Sciences; 15. Life on land; Iowa; Tennessee; Computer science; Carbon; Earth and Planetary Sciences; World Wide Web; 13. Climate action; FOS: Biological sciences; Environmental Science; Physical Sciences; Soil Carbon Dynamics and Nutrient Cycling in Ecosystems; Ecosystem Functioning

AbstractGlobal soil organic carbon (SOC) stocks may decline with a warmer climate. However, model projections of changes in SOC due to climate warming depend on microbially-driven processes that are usually parameterized based on laboratory incubations. To assess how lab-scale incubation datasets inform model projections over decades, we optimized five microbially-relevant parameters in the Microbial-ENzyme Decomposition (MEND) model using 16 short-term glucose (6-day), 16 short-term cellulose (30-day) and 16 long-term cellulose (729-day) incubation datasets with soils from forests and grasslands across contrasting soil types. Our analysis identified consistently higher parameter estimates given the short-term versus long-term datasets. Implementing the short-term and long-term parameters, respectively, resulted in SOC loss (–8.2 ± 5.1% or –3.9 ± 2.8%), and minor SOC gain (1.8 ± 1.0%) in response to 5 °C warming, while only the latter is consistent with a meta-analysis of 149 field warming observations (1.6 ± 4.0%). Comparing multiple subsets of cellulose incubations (i.e., 6, 30, 90, 180, 360, 480 and 729-day) revealed comparable projections to the observed long-term SOC changes under warming only on 480- and 729-day. Integrating multi-year datasets of soil incubations (e.g., > 1.5 years) with microbial models can thus achieve more reasonable parameterization of key microbial processes and subsequently boost the accuracy and confidence of long-term SOC projections.